In air moving apparatus incorporating blowers, the blower wheels are supported within blower housings which are typically dimensioned and positioned such that relatively close running tolerances are maintained in the interest of maximizing blower efficiency. In direct drive applications, the motor is suspended from the blower housing, and a motor shaft in turn supports and drives the blower wheel within the housing. Examples of apparatus wherein mounting arrangements of this type are utilized include room air conditioners, air circulation fans, and the like.
In applications where the blower is mounted directly to the motor shaft, it is believed to be desirable to isolate motor vibrations from the housing structure so as to minimize the transmission of noise thereby achieving quieter operation. Not only must mounting arrangements reduce the transmission of motor vibration, but they must provide sufficient mounting rigidity to avoid excessive axial and tilting movement of the motor during operation. In the past, to achieve these ends, motor mounting arrangements have been provided with mounting arms which had low torsional spring constants, and yet had sufficient strength to withstand not only the vibrations encountered during operation but also the shipping and handling loads for the motor and blower assemblies. The spring constants of the mounting arms for the axial, radial and tilting vibration modes were selected so that the characteristic vibration transmissibility ratios for these modes were close to unity. However, the characteristic torsional mode of vibration transmissibility was substantially less than unity because of the flexibility of the arms. Such prior art mounting arrangements are disclosed in U.S. Pat. No. 4,063,060 issued Dec. 13, 1977 to Ernest W. Litch III and U.S. Pat. No. 4,076,197 issued Feb. 28, 1978 to Richard W. Dochterman, and each of such patents are incorporated herein by reference.
In many instances in the past, it has been desirable to permanently attach mounting arms to a motor shell or housing when manufacturing original equipment motors. For a replacement or aftermarket motor, however, it has been more customary to mount such motor by various different means, such as for instance bolts, welded straps, or bands removably affixed to a housing of such motor. This is believed not only to have avoided the necessity for purchasing a motor which had a mounting arrangement customized to a particular application but also to have afforded much more flexibility in selecting a replacement motor. The mounting arms, which may have been of the type disclosed in the aforementioned Litch and Dochterman patents, may have been connected to straps or bands by suitable means, such as welding for example.
In past, many electric motors included vent or other openings or the like, which have been arranged generally in a circular array adjacent one end of the motor housing with another similar array of such vent openings located near the other end of the motor housing. During operation of these motors, air flowed through the vent openings and was utilized to cool the windings and the bearings of the motor. Although the primary purpose of the aforementioned vent openings was to enable greater cooling of the motor, they have, in the past, been utilized to provide a spaced connection between the motor housing and a mounting band or strap or the like which encircled the motor housing to enable mounting of the motor to a member which was adapted to support a motor having a larger peripheral configuration. Such a mounting arrangement is disclosed in U.S. Pat. No. 3,848,837 issued Nov. 19, 1974 to Richard W. Dochterman. In this patent, clip members either straddled the portions of the motor housing between the vent openings or were insertable within the vent openings, and the band or strap was supported thereon. In either event, the clips interlocked with the vent openings in a resilient fashion.
In the aforementioned U.S. Pat. Nos. 4,063,060 and 4,076,197, the mounting arms thereof were rigidly connected to a housing of an electrical motor. Although these mounting arrangements were accomplished by welding the mounting arms directly to the motor shell, as was customarily done during manufacturing of original equipment motors, such a mounting arrangement was not feasible in the case of replacement motors which required a wide variety of mounting arm lengths and configurations to properly mount such replacement motors into various blower housings.